JP5293989B2 - Small liquid spray equipment - Google Patents

Abstract

A spray device includes an opening gap between a needle-shaped needle tip and a first nozzle hole. The gap is adjusted by a very tiny amount by a needle movement amount adjustment device, and liquid oozes from the first nozzle hole along the needle tip part. The liquid is formed into tiny particles by a first atomization compressed gas flowing through the first atomization compressed gas passage and is exhausted from a second nozzle hole. The exhaust flow passes through a third nozzle hole and is exhausted. The third nozzle's second atomization/eddy flow formation compressed gas collides with this exhaust flow, so the exhaust flow is made into even smaller particles, and swirls and disperses, and is applied to the coated object.

Description

  The present invention is applied to a coating such as a semiconductor silicone wafer, a glass substrate, various resins, and a metal member by atomizing a liquid such as a liquid photoresist agent, a surface protective film, and a functional coating agent in an extremely fine manner. The present invention also relates to a spray device (spray gun) for a small amount of liquid for forming a thin film.

  Conventionally, when a resist agent or a functional film having a dry film thickness of 10 μm or less is formed on a semiconductor silicone wafer or a glass substrate, a coating technique such as a spin coater or a bar coater has been actively used.

  However, if the surface of the semiconductor silicone wafer or glass substrate is flat or the surface on which the resist agent is applied is flat, it may be fine. It is difficult to form a film with a spin coater or a bar coater or the like when the object to be coated flies at the time of rotation or a spherical object or a cylindrical object whose shape cannot be rotated. In addition, when the coated surface is uneven (the aspect ratio is large), or the dent or hole is vacant, the uneven surface, the side surface of the dent, the bottom surface, the side surface of the hole, etc. cannot be applied.

  Therefore, a method of forming a coating material with a spray gun is considered. However, in order to obtain a dry film thickness of 10 μm or less, the particle diameter obtained by atomizing the liquid is usually about 10 μm to 20 μm. As a result, it takes time to determine the setting of the coating conditions, and it becomes difficult to obtain a highly accurate film thickness. When sprayed with a general air spray gun, the particle size of the coating material was at most about 10 to 15 μm even when the viscosity was lowered to 20 CPS or less.

  In that case, when the coating particles adhere to and deposit on the uneven portion having a step of 20 μm, since the particle diameter is large, the corner of the concave portion droops and becomes thin. In order to make the particle diameter finer to 10 μm or less, it cannot be formed unless the atomizing air pressure is set to 0.4 MPa or more and the discharge amount is lowered. In that case, the atomization pressure is too strong, and particles of 10 μm or less are difficult to adhere to the object to be coated, and the coating efficiency falls to 30% or less, which makes it impossible to apply as a coating apparatus. The film thickness accuracy in spraying is generally ± 10% or more when the dry film thickness is usually 10 μm by flat coating.

  When forming a thin film of 10 μm or less, the air atomization spray is the most common and inexpensive in the spray method. There are other spray guns that use an ultrasonic atomization method that allows fine atomization, but on the contrary, the spray speed is too slow and it is difficult to adhere to the object to be coated. Is. In the airless spray method and centrifugal atomization method, the viscosity of the liquid is reduced to 20 CPS or less, and particles of 10 μm or less are formed only about 20% of the entire discharge at a location 300 mm or more away from the spray ejection outlet. In addition, there is a drawback that a low discharge amount corresponding to the object to be coated of 30 cc or less per minute cannot be produced. Therefore, a two-fluid spray method by air atomization is usually considered for forming a thin film of 10 μm or less. However, as described above, the coating efficiency is as low as about 20 to 30%, and the biggest drawback is that the coating film thickness accuracy of a thin film region of 10 μm or less reaches ± 5% or less like a spin coater. could not.

  Therefore, it is conceivable to apply a spray method called an air brush which is a special spray method even in air spray. This airbrush is often used as a small spray handheld gun for painting plastic model parts and small products. The nozzle diameter is 0.5mmφ or less, and the needle used for paint spray control is a needle. It has a shape, and when the paint adheres and flows along the needle-shaped needle, the surrounding compressed air atomizes the paint by the ejector effect. The discharge amount can be reduced to 5 cc or less per minute, and even if the spray nozzle is close to around 10 mm, fine particles of 10 μm or less can be formed, and the coating efficiency is as high as 80% or more because the spray nozzle is close. It is possible to paint on the object.

On the other hand, for example, a two-stage liquid atomization method as shown in Patent Document 1 is known as a method for atomizing coating by an air spray method. In this atomization method, liquid is atomized with compressed air in the first stage, and swirling air is applied to the liquid jet stream in the second stage to further promote atomization and apply as a swirl jet stream.

  In the spray method using the airbrush, it is difficult to control a small amount or a small amount of discharge. That is, the adjustment of the discharge amount is a method in which the needle is manually adjusted, and there is a problem that the quantitative control adjustment requires considerable skill, and therefore automatic coating is difficult. Furthermore, this spray method has a problem that the applied atomization pattern width is as narrow as about 5 mm.

  Further, the atomization coating apparatus disclosed in Patent Document 1 has an advantage that the atomization pattern can be widened as compared with the airbrush system, but there is a problem that it is difficult to adjust the supply of a small amount of liquid.

  The present invention is intended to solve the problems of the above-described conventional liquid spraying device, and is equivalent to or higher than the level at which ultrafine particles are formed by ultrasonic atomization or airbrush spraying. It is possible to easily and reliably adjust the supply of a desired amount of a small amount or a small amount of liquid by forming fine particles, and to apply and adhere efficiently to an object to be coated. A semiconductor silicone wafer or a glass substrate And a spraying device for a small amount of a liquid that forms a thin film by spray coating a liquid or a melt such as a liquid photoresist agent, a surface protective film and a functional coating agent on an object to be coated such as various transparent members It is intended.

In order to achieve the above object, the present invention employs a spraying apparatus for a small amount of liquid as follows.
That is, a spraying device for atomizing a small amount of liquid and applying it to an object to be coated,
A liquid supply passage;
The tip is needle-shaped and the needle is very thin with a uniform gradient to the tip .
A valve mechanism is formed between the tip of the needle and has a very fine first nozzle hole having a shape corresponding to the needle tip, and the needle tip can be inserted into and removed from the first nozzle hole. A first nozzle that can be fitted to
A second nozzle that surrounds the first nozzle and forms an annular first atomizing compressed gas passage between the first nozzle and a second nozzle hole having a small diameter at the lower end;
The third nozzle of the third nozzle is formed at the lower end of the second nozzle so as to surround the second nozzle hole of the second nozzle and the lower end protrudes from the lower surface of the second nozzle by a predetermined distance. hole is formed, around the third nozzle holes, to flow compressed gas for the second atomization and swirling flow formed along the opposite conical inclined surface is an outer wall, said second atomization A third nozzle formed with a plurality of compressed gas supply passages for forming a swirl flow for use;
A needle movement amount adjusting device which is provided so as to be in contact with a rear end portion of the needle, and which can adjust a very small amount of an opening gap between the tip portion of the needle needle and the first nozzle hole of the first nozzle;
With
The tip of the needle protrudes to the inside of the third nozzle hole of the third nozzle with the valve mechanism opened, and the liquid goes to the tip between the first nozzle hole and the needle tip. A structure that oozes along the tip of the ultrafine needle while passing through a very small gap as the annular gap becomes smaller,
While the liquid is discharged, the second nozzle is atomized by the first atomizing compressed gas flowing through the first atomizing compressed gas passage while the liquid oozes from the first nozzle hole of the first nozzle along the tip of the needle. Jetting from the second nozzle hole of the nozzle, and then causing the jet stream to jet through the third nozzle hole of the third nozzle and causing the compressed gas for forming the second atomization and swirl flow to collide with the jet stream, The sprayed flow is further atomized, swirled and diffused, and applied to an object to be coated.

  Thus, when the liquid is discharged, the opening gap between the needle needle tip and the first nozzle hole can be adjusted by a very small amount by the needle movement amount adjusting device, and the liquid oozes from the first nozzle hole along the needle tip. The liquid is atomized by the first atomizing compressed gas flowing through the first atomizing compressed gas passage while being ejected and ejected from the second nozzle hole, and the ejected flow is ejected through the third nozzle hole to perform the third. By causing the compressed gas for forming the second atomization and swirl flow of the nozzle to collide with the jet flow, the jet flow can be further atomized, swirled and diffused, and applied to the object to be coated.

  In adjusting the liquid discharge amount, the opening gap amount between the needle needle tip and the first nozzle hole can be adjusted by a needle movement amount adjusting device. The degree of opening can be adjusted in units of 8 to 15 μm, preferably in units of 10 μm, and atomization can be performed with the first atomizing compressed gas. Thus, for example, by attaching a needle movement amount adjusting device capable of adjusting the pulling amount of the needle by a value such as a unit of 10 μm, reproducibility of the discharge amount every time the valve is opened and closed is ensured, and stable discharge can be obtained.

  In this case, a micro adjustment can be used as the needle movement amount adjusting device. Therefore, the control and adjustment of the liquid discharge amount does not require manual adjustment of the needle as in the prior art, and quantitative discharge amount control can be performed with good reproducibility and automated coating. Can be done.

The spray device of small volume liquid This tip portion of the needle is sharp long thin at a uniform slope to the tip, the third nozzle of the third nozzle while the tip portion of said needle valve mechanism is opened so as to be positioned protruding to the inside of the hole, the liquid, oozing along the microfine needle tip while through the minimum gap annular gap becomes smaller toward the distal end between the first nozzle hole and the needle tip configuration Has been. As a result, a small amount of liquid is stably guided to the downstream object and discharged.

Then, the stable flow of the liquid is atomized by the negative pressure effect by the compressed gas flow for the first atomization of, for example, a pressure of 0.1 to 0.3 MPa around the liquid, for example, an opening diameter of 0.8 It is ejected from the second nozzle hole of ˜1.5 mm. The jet flow further passes through a third nozzle hole having an opening diameter of 1.0 to 2.0 mm, and is jetted from a plurality of compressed gas supply passages of the third nozzle, for example, a second atomization having a pressure of 0.1 to 0.3 MPa. Further compression of the liquid atomization and diffusion of the atomization pattern area are performed by collision diffusion by the compressed gas flow for forming the swirl flow.
At this time, a third nozzle formed at the lower end portion of the second nozzle so as to surround the second nozzle hole of the second nozzle and the lower end portion protrudes a predetermined distance from the lower surface of the second nozzle. Since the third nozzle hole is formed, the jet flow ejected from the second nozzle hole is converted into a flow of compressed air for second atomization and swirl formation in the protruding internal space of the third nozzle hole. Since there is no influence, the first stage liquid atomizing action performed between the first nozzle and the second nozzle is stably performed while being stably ejected in the direction of the object to be coated below.
Further, the third nozzle is configured such that the compressed gas for forming the second atomizing and swirling flow flows around the third nozzle hole along the reverse conical inclined surface which is the outer wall. Since the plurality of compressed gas supply passages for forming the two atomizing and swirling flow are formed, the compressed air flow for forming the second atomizing and swirling flow ejected from the compressed air supplying passage is formed on the inclined surface. A stable swirl flow that flows along the entire circumference is formed, and this swirl flow collides with a jet flow ejected from the third nozzle hole, thereby forming a swirl jet flow without a stable turbulence. As a result, the jet flow is stably and finely atomized.

Further, in the small amount liquid spraying device, the viscosity of the liquid supplied to the liquid supply passage is a low viscosity of 10 to 100 CPS, and the outlet opening diameter of the first nozzle hole of the first nozzle is 0.2 to 0.6 mm, the angle of the needle-shaped needle tip is 3 to 10 degrees, the inner diameter of the second nozzle hole of the second nozzle is 0.8 to 1.5 mm, and the third nozzle The opening diameter of the third nozzle hole is 1.0 to 2.0 mm, and the opening gap between the needle needle tip and the first nozzle hole of the first nozzle by the needle movement amount adjusting device is extremely small. The moving distance of the needle for adjustment can be adjusted every 8 to 15 μm (in units), and a small amount of liquid is atomized and applied by setting the liquid discharge amount to 0.1 to 10 cm ³ / min. This is a small amount liquid spraying device.

Thereby, a small amount of liquid can be applied efficiently and accurately. That is, while the liquid having a low viscosity of 10 to 100 CPS and a discharge amount of 0.1 to 10 cm ³ / min is stably guided along the tip of the needle to the downstream object, the first to third nozzles are Two-stage atomization can be achieved by passing. The angle of the needle-shaped needle tip is 3 to 10 degrees, more preferably 4 to 6 degrees. When the unit of movement distance of the needle is smaller than 8 μm, the annular gap between the first nozzle hole and the needle tip portion becomes too small due to the angle of the needle tip portion, and the liquid is stably stabilized. If it is larger than 15 μm, the annular gap becomes too large, and stable atomization becomes difficult.

As the outlet opening diameter of the first nozzle hole is smaller, the discharge flow rate can be reduced. However, if it is smaller than 0.2 mm, the nozzle hole is likely to be clogged. On the other hand, if it is larger than 0.6 mm, it is difficult to achieve a target value for atomizing a very small amount of liquid such as a discharge amount of 0.2 to 5.0 cm ³ / min. In consideration of the above points, the outlet opening diameter of the first nozzle hole is more preferably 0.3 to 0.5 mm. If the second nozzle opening diameter is smaller than 0.8 mm, it is difficult to atomize the liquid by the first atomizing compressed gas flow due to the relationship with the first nozzle outlet diameter, and the opening diameter is larger than 1.5 mm. It is difficult to secure a stable jet flow. When the third nozzle diameter is smaller than 1.0 mm, the jet flow from the second nozzle hole is not stably discharged, and when larger than 2.0 mm, the second atomizing swirl is discharged from its surroundings. It becomes difficult to impinge on the jet flow by the compressed gas flow for flow formation.

  As described above, the spray device for a small amount of liquid according to the present invention can control and adjust the discharge amount of a small amount of liquid with a low viscosity easily and surely. Therefore, quantitative discharge amount control can be performed with good reproducibility. For this reason, automatic coating can be performed. And, liquid such as liquid photoresist agent, surface protective film and functional coating agent can be atomized widely without reducing coating efficiency, semiconductor silicone wafer, glass substrate, various resins, metal members, etc. A thin film can be formed on the object to be coated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system diagram of use of a low discharge amount automatic liquid jet head as a small amount liquid spraying apparatus according to the present invention. FIG. 2 is a low discharge amount liquid automatic discharge head as a small amount liquid spraying apparatus according to the present invention. FIG. 3 is an enlarged view of a portion A in FIG. 2 and an enlarged detailed view of the first to third nozzles. FIG. 4 is a bottom view of FIG. 3 and a bottom view of the third nozzle.

  Reference numeral 1 denotes a low ejection amount liquid ejecting head. The low ejection amount liquid ejecting head 1 includes a liquid supply pipe 6 for quantitatively supplying the liquid stored in the liquid tank 4 by a liquid supply constant supply pump 6b. Have. The liquid supply pipe 6 is provided with a liquid supply switching valve 6a downstream of the liquid supply quantitative supply pump 6b, and the low discharge amount liquid ejecting head 1 performs a liquid discharging operation on the switching valve 6a. A liquid return pipe 6c is provided for returning the liquid to the liquid tank 4 when not. The flow direction of the liquid is switched when the operation of the head driving solenoid valve 3a stops, that is, the needle tip 8A is pushed back into the first nozzle hole 7a of the first nozzle 7 by the elastic force of the spring 2F. Is closed, the liquid supply switching valve 6a is operated, and the liquid is switched from the liquid supply pipe 6 to the liquid return pipe 6c.

  Further, the low discharge amount liquid jet head 1 includes a first-stage atomized compressed air supply pipe 5 as a first atomized compressed gas, and a second atomizing and swirl flow forming compressed gas as a compressed gas. The second-stage atomized compressed air supply pipe 11 is connected, and the compressed air pressure can be adjusted by the respective atomizing air regulators 5b and 11b. The compressed air for the first stage atomization is operated by the electromagnetic valve 5a for the first stage atomization, and the compressed air for the second stage atomization is used for the low discharge amount by the operation of the electromagnetic valve 11a for the second stage atomization. It flows to the liquid jet head 1. As the operation order of the respective solenoid valves, the first stage atomizing solenoid valve 5a is normally operated, and the head driving solenoid valve 3a and the second stage atomizing solenoid valve 11a are operated substantially simultaneously after about 50 ms. Is suitable for optimal atomization of liquids.

  The liquid ejection head 1 for low discharge amount is provided with a long and fine needle body 8 positioned at the center so as to be movable up and down, and an air piston 2B is fixed to the upper end portion of the needle body 8. Between the air piston 2B and the air piston cover 2A, the needle body 8 is always pressed downward, the needle tip 8A is a needle-like, long and sharp needle, and the first nozzle hole of the first nozzle 7 The spring 2F for closing the valve mechanism comprised between 7a is interposed. A liquid supply passage 6A is formed between the needle body 8 and the surrounding head body 1a, and a first nozzle 7 is fixedly provided at the lower end of the head body 1a. The first nozzle 7 is formed with a first nozzle hole 7a into which the needle tip 8A can be removably fitted with a taper shape corresponding to the shape of the needle tip.

  An annular first atomizing compressed gas passage 5 </ b> A is formed outside the first nozzle 7 so as to surround the first nozzle 7 and decrease in cross-sectional area with the first nozzle 7. A second nozzle 9 having a small-diameter second nozzle hole 9a narrowed around the outlet opening of the first nozzle hole 7a is fixedly attached to the head main body 1a. That is, the inner wall surface of the second nozzle 9 is formed in an inverted conical shape, and the lower end is narrowed to form a second nozzle hole 9a having a small diameter D2. A third nozzle 10 is fixedly attached to the lower end portion of the second nozzle 9, and the third nozzle 10 surrounds the second nozzle hole 9a of the second nozzle 9 at its outlet opening. Is formed.

  Further, as shown in FIG. 4, the third nozzle 10 has the same center around the center of the first nozzle hole 7A and the second nozzle hole 9a, that is, the axial center of the needle needle tip 8A, as seen in a plan view. A plurality of second atomization and swirl flow forming compressed air supply passages 10b are formed at equal intervals on the circumference and inclined and drilled in a front view. The lower end of the third nozzle 10 protrudes a predetermined distance from the lower surface of the second nozzle 9 to form the third nozzle hole 10a, and the outer wall of the third nozzle hole 10a has an inverted conical inclined surface 10c. Is formed. Thereby, the compressed air flow for forming the second atomization and swirl flow ejected from the compressed air supply passage 10b flows along the inclined surface 10c, and forms a stable swirl flow rectified on the entire circumference. The swirl flow collides with the jet flow ejected from the third nozzle hole 10a to form a swirl jet flow without a stable turbulence. As a result, the jet flow is stably and finely atomized.

  Note that the jet flow ejected from the second nozzle hole 9a is not affected by the flow of compressed air for second atomization and swirl formation in the protruding internal space of the third nozzle hole 10a. The first-stage liquid atomization action performed between the first nozzle 7 and the second nozzle 9 is stably performed.

  The third nozzle is attached to the head main body 1a with a presser nut 11B, and the presser nut 11B is formed in a box shape inside, between the second nozzle 9 and the outer side of the third nozzle 10. A compressed air passage 11A for second stage atomization is configured.

  At the upper end of the liquid ejection head 1 for low discharge amount, a micro as a needle movement amount adjusting device capable of adjusting a very small opening gap between the needle needle tip 8A and the first nozzle hole 7a of the first nozzle 7 is provided. An adjustment 2C is attached, and a micro adjustment end 2D is formed at the lower end of the micro adjustment 2C. The micro-adjusted end 2D is provided so as to be in contact with the rear end portion (upper end portion) of the needle body 8.

When the liquid having a low viscosity of 10 to 100 CPS and a discharge amount of 0.1 to 5.0 cm ³ / min is atomized and applied, the outlet opening diameter D1 of the first nozzle hole 7a of the first nozzle 7 is set to 0.00. 2 to 0.6 mm, the angle of the needle-shaped needle tip 8A is 3 to 10 degrees, and the inner diameter D2 of the second nozzle hole 9a of the second nozzle 9 is 0.8 to 1.5 mm. The opening diameter D3 of the third nozzle hole 10a of the third nozzle 10 is 1.0 to 2.0 mm, and the opening of the needle-shaped needle tip 8A and the first nozzle hole 7a by the micro-adjustment 2C The moving distance of the needle for adjusting the minute amount of the gap can be adjusted every 8 to 15 μm (in units).

  In the liquid ejection head 1 for low discharge amount thus configured, the compressed air flows from the head driving compressed air pipe 3 into the valve air piston portion 2 by the operation of the head driving solenoid valve 3a. The piston 2B moves toward the micro adjust 2C against the elastic force of the spring 2F, and the rear end portion of the needle body 8 connected to the air piston 2B is abutted against the micro adjust end 2D. The stroke is stopped at a fixed position, and the gap in the diameter direction between the first nozzle hole 7a and the needle tip 8A is kept at a predetermined interval.

  A fine gap is formed between the needle tip (8A) of the needle body (8) and the first nozzle hole 7a away from the first nozzle hole 7a, and the liquid in the in-head liquid supply passage 6A is liquid. The first-stage atomization that flows out from the first-stage atomization compressed air supply passage 5A in the head at the same time as being extruded from the inside of the first nozzle hole 7a to the surface of the needle tip 8A by the pumping pressure of the supply quantitative supply pump 6b. Due to the ejector effect of the compressed air for use, the liquid on the surface of the needle tip 8A is sucked and drawn out from the outlet (lower end) opening of the first nozzle hole 7a, and the liquid drawn from the outlet opening of the first nozzle hole 7a. Are atomized, that is, atomized by the compressed air for the first stage atomization, are sent out as a jet flow from the second nozzle hole 9a of the second nozzle 9 and into the third nozzle hole 10a of the third nozzle 10. This First stage atomization pattern 12 is formed in.

  And the 1st stage atomization pattern 12 which is the jet flow of the liquid fine particle formed by atomization is for 2nd atomization of the 3rd nozzle 10 via the compressed air supply passage 11A for 2nd stage atomization. The atomized compressed air flowing out from the compressed air supply passage 10b for forming the swirl flow is further atomized by the ejector effect and swirled to form a swirl flow, and the swirl pattern second step atomization pattern 13 Is formed and attached to the object 14 to be coated.

  In the present invention, a liquid photoresist agent, a surface protective film, and a functional coating agent are used as the liquid as the coating agent, and examples of the coating object include a semiconductor silicone wafer, a glass substrate, various resins, and a metal member. Applied.

  As described above, in the present embodiment, the needle tip 8A, which serves as a valve for controlling liquid discharge, with respect to the first nozzle 7 having the first nozzle hole 7a having an outlet opening diameter of 0.2 to 0.6 mmφ. Has an acute angle structure of 3 to 10 °, and protrudes to the first nozzle hole 7a of the first nozzle 7, the second nozzle hole 9a of the second nozzle 9, and further to the nozzle hole 10a of the third nozzle 10. When the liquid is ejected, the air opening is made into a structure in which the opening as the needle pulling allowance can be adjusted in units of 8 to 15 μm. By attaching the micro-adjustment 2D in which the pulling amount of the needle 8 can be adjusted in units of 8 to 15 μm, the reproducibility of the discharge amount every time the valve is opened and closed is ensured, and stable discharge is obtained.

  In the liquid discharge, when the liquid oozes out along the ultrafine needle tip 8A, the liquid is atomized by the negative pressure effect by the compressed air flow for the first stage atomization at a pressure of 0.1 to 0.3 Mpa around it, A pressure of 0.1 to 0. 0 is ejected from the second nozzle hole 9a of the second discharge nozzle 9 having a diameter of 0.8 to 1.5 mm and from the third nozzle hole 10a of the third nozzle 10 having a diameter of 1.0 to 2.0 mm. With the compressed air flow for the second stage atomization and vortex of 3 Mpa, further atomization of the liquid can be promoted and the atomization pattern region can be diffused by collision diffusion.

  That is, in this embodiment, the ejection head 1 that sprays liquid at a low ejection amount controls the liquid ejection of the low viscosity liquid of 10 to 100 CPS to the first to third ejection nozzles 7, 9, and 10. The spray pattern 15 having a trapezoidal distribution of a round spray projecting from an acute needle tip 8A can be efficiently applied and adhered to the article 14 to be coated.

  That is, in the low discharge amount liquid jet head 1 of the present embodiment, a low viscosity liquid of 10 to 100 CPS is supplied to the first nozzle 7 having the first nozzle hole 7a having an outlet diameter of 0.2 to 0.6 mmφ. An acute needle tip 8A having an angle of 3 to 10 ° for controlling liquid discharge is provided, and the needle tip 8A protrudes to the first nozzle hole 7a, the second nozzle hole 9a, and the third nozzle hole 10a. When the liquid oozes out along the needle tip 8A during the liquid discharge, the liquid is sprayed by the negative pressure effect by the air flow of the surrounding first stage atomizing compression air pressure 0.1-0.3Mpa. Compressed air for second-stage atomization is ejected from the second nozzle hole 9a of the second discharge nozzle 9 having a diameter of 0.8 to 1.5 mmφ and from the third nozzle 10 having a diameter of 1.0 to 2.0 mmφ. Pressure of 0.1-0.3 Mpa By having a microadjustment 2D that can control the moving distance of every 8 to 15 μm of the needle part 8 provided at the rear part of the head while diffusing the atomization region and the accelerating atomization region of the liquid by collision diffusion by the spiral air flow. Since the gap between the nozzle 7 and the needle tip 8A can be extremely finely adjusted, a small amount of low-viscosity liquid can be discharged.

  As described above, in this embodiment, the liquid can be widely atomized without lowering the coating efficiency. For example, the liquid automatic for low discharge amount for forming a thin film of 0.1 to 10 μm can be obtained. An ejection head (spray gun) 1 can be obtained.

  Further, in the automatic ejection head 1 of the present embodiment, when a liquid resist agent is spray-coated on an object to be coated having a step pattern, for example, a semiconductor silicone wafer, the particles are miniaturized and the solvent is evaporated. By increasing the liquid viscosity, it is minimized that the coating film hangs down even at the corners (edges) of the convex portions and concave portions of the step, and a film having a predetermined thickness, for example, 6 to 10 μm, is formed. Thus, a uniform film formation can be applied as a whole.

  The flow rate distribution 15 of the second-stage atomization pattern 13 when the second-stage atomization pattern 13 having a spiral pattern is formed and attached to and coated on the workpiece 14 is approximately two-thirds of the entire pattern. (2/3) is a flat trapezoidal distribution. The flow rate distribution 15 of the atomization pattern varies depending on the first-stage atomization compressed air supply pressure and the second-stage atomization compressed air supply pressure (or flow rate). A flat trapezoidal distribution is obtained when the compressed air pressure for atomization is substantially the same, but the compressed air supply pressure for the second stage atomization is less than half of the compressed air supply pressure for the first stage atomization. And it changes.

Next, the measurement experiment results will be described.
FIG. 5 shows the pattern flow rate distribution of the film thickness measurement result when the low ejection amount liquid jet head 1 is moved on one straight line. As can be seen in FIG. 5, the first stage atomization compressed air pressure and the second stage atomization compressed air pressure, which are the application conditions of (3) and (4), are around 0.1 Mpa to 0.15 Mpa, respectively. The flow rate distribution 15 of the atomization pattern is a trapezoidal distribution in which approximately 2/3 of all patterns are flat. If the compressed air pressure for the second stage atomization is increased, the pattern width tends to widen, but the film thickness is lower than the expected number. This is thought to be due to a decrease in coating efficiency. If the compressed air pressure for the second stage atomization is not increased too much, the coating efficiency can be maintained and a relatively stable trapezoidal distribution can be achieved. When the coating efficiency was measured, (1) was 88%, (2) 86%, (3) 82%, (4) 79%, (5), (6) 76% or less.

  FIG. 6 shows the increase in liquid viscosity after spraying with the distance from the nozzle to the surface to be coated under the coating conditions (1), (2), (3) and (6). If the compressed air pressure for atomization rises, the amount of air also increases and the atomized viscosity of the liquid tends to increase. This is because the solvent evaporates more and the solid content increases. In particular, the conditions (3) and (6) mean that the coating film after spraying is difficult to sag.

(Measurement 1)
Measurement of the flow distribution 15 of the atomization pattern.
(1) Liquid viscosity 20 CPS.
That is, with the stock solution AZ P4330 (NV value 30%) as a diluent solvent with a weight ratio of 1, propylene glycol monomethyl ether acetate is added with a weight ratio of 1 and the solid content ratio is 15% (volume NV value 0.11%) and the viscosity is 20 CPS Obtained liquid.
(2) The specific gravity of the liquid is 1.33.
(3) The liquid supply metering pump 6b is a gear pump and has a discharge pressure of 1.5 cc / min (min) at a hydraulic pressure of 0.01 Mpa.
(4) The distance between the nozzle and the object to be coated is 40 mm.

(5) The first stage atomization compressed air pressure is changed by 0.1 Mpa to 0.25 Mpa, respectively.
(6) The two-stage atomization compressed air pressure is changed by 0.02 Mpa to 0.25 Mpa, respectively.
(7) The speed when the low ejection amount liquid jet head 1 is moved on one straight line is 900 mmm / min.
(8) Measurement of the film thickness when the low ejection amount liquid jet head 1 is moved on one straight line.
The film thickness measurement at that time is shown in FIG. 5, and the viscosity increase measurement after spraying the liquid is shown in FIG. Table 1 shows the coating conditions (1) to (6) in FIG.

  Based on the above conditions, the low ejection volume liquid jet head 1 is mounted on an orthogonal manipulator operating in the X, Y and Z axis directions, and the coating film formation results on the flat substrate are as follows: Describe.

(1) Low discharge amount liquid jet head The discharge flow rate of the first nozzle 7 is reduced as the hole diameter for discharging the coating material (liquid) is smaller. In this experiment, the first nozzle 7 having a small diameter with an outlet opening diameter D1 of the first nozzle hole 7a of 0.3 mmφ, and the needle 8 are needles with an inclination of 5 ° (degrees) from the tip. Taper needle. The low ejection amount liquid jet head was mounted on an orthogonal manipulator operating in the X, Y and Z axis directions, and the both ends of the splay pattern were wrapped and applied.

(2) Coating material As a liquid resist agent, a solid content ratio obtained by adding a stock solution AZ P4330 (NV value 30%) manufactured by Client Japan Co., Ltd. to a weight ratio 1 and propylene glycol monomethyl ether acetate 1 in a weight ratio 1 A viscosity of 20 CPS was optimal at 15%. The results were good even at other viscosities of 30 to 50 CPS.

(3) Discharge fluid pressure 0.015 MPa
(4) Application room temperature and relative humidity 20 ° C 65%
(5) Coated object 200 mm square flat glass plate,
And a 6-inch wafer on which a pattern having a width of 25 μm and a height of 50 μm is mounted.
(6) Target coating film thickness Within 3 μ ± 5% (3σ) with respect to the flat glass surface.
Targets of 6μ to 10μ on each side and corners for 6 inch wafer with stepped pattern.

(7) Other application conditions Nozzle moving speed (X axis) 300 mm / min
40mm distance between nozzle and substrate
Discharge rate 1.5cc / min
Number of coatings 1 time Surface temperature at coating object 30 ° C

Compressed air pressure for first stage atomization 0.15 MPa (hereinafter referred to as atomizing air pressure)
Compressed air pressure for second stage atomization 0.1 MPa (hereinafter referred to as pattern air pressure)
Application pitch 10mm
Drying conditions after coating 100 ° C
Drying time: 3 minutes As a result of the experiment under the above conditions, a desired good coating state was obtained. The results of the application state are shown in Table 2.

Target value of the above data = 30.000 film thickness [Å], accuracy 5%
The amount of coating used is 3 cc with a flat glass plate of 200 squares.
In this case, if the target accuracy is 5%,
USL = 31,500, LSL = 28,500, UCL = 30,330, LCL = 29,773, #of exc. = 0.0, #of samp = 96, average film thickness = 30051.5, Min film thickness = 30,002, Max film thickness = 30,810, diff. = 0.17%, Cp = 5.391, Cpk = 5.206, Stdev. = 92.8, 3 Sigma = 278.3, 3 Sigma% = 0.93%.
The particle size distribution measurement result at this time is shown in FIG.

  It is a systematic diagram of the use of a liquid ejection head for low discharge amount as a small amount liquid spraying apparatus of the present invention.   It is a longitudinal cross-sectional view of the liquid automatic ejection head for low discharge amount as a small amount liquid spraying device of the present invention.   FIG. 3 is an enlarged view of a part A in FIG. 2, and is an enlarged detailed view of first to third nozzles.   FIG. 4 is a bottom view of FIG. 3 and is a bottom view of a third nozzle.   It is a graph which shows the measurement result of an application pattern, and is a graph which shows the relation between application width and film thickness.   It is a graph which shows the viscosity-up measurement result after spraying a liquid, and shows the relationship between the distance from a nozzle to a to-be-coated object, and a viscosity.   It is a graph which shows the particle size distribution measurement result on the application | coating conditions in the compressed air pressure for the 1st stage atomization in (1) of Table 1, and the compressed air pressure for the 2nd stage atomization.

Explanation of symbols

1 Liquid ejection head for low discharge volume (Small liquid spraying device)
1a Injection head body 2 Valve air piston part 2A Air piston cover 2B Air piston 2C Micro-adjustment (needle movement amount adjusting device)
2D Micro adjustment end 2E Piston seal O-ring 2F Spring 3 Head drive compressed air pipe 3a Head drive solenoid valve 3b Head drive air regulator 4 Liquid tank 5 First stage atomization compressed air supply pipe 5a First stage fog Electrostatic valve 5b 1st stage atomizing air regulator 5A In-head first stage atomizing compressed air supply passage 6 Liquid supply pipe 6a Liquid supply switching valve 6b Liquid supply fixed supply pump 6c Liquid return pipe 6A Liquid in head Supply passage 7 First nozzle 7a First nozzle hole 8 Needle body 8A Needle tip 8B Liquid seal O-ring 9 Second nozzle 9a Second nozzle hole 10 Third nozzle 10a Third nozzle hole 10b Second atomization and swirl Flow forming compressed air passage 10c Inclined surface 11 Second stage atomizing compressed air supply pipe 11a Second stage atomizing solenoid valve 11 Second stage atomization air regulator 11A Compressed air passage 11B for second stage atomization in the head Third nut pressing nut 12 First stage atomization pattern 13 Second stage atomization pattern 14 Object 15 Atomization pattern Flow distribution D1 Outlet opening diameter D2 of the first nozzle hole D2 opening diameter of the second nozzle hole D3 Opening diameter of the third nozzle hole

Claims (2)

A spraying device for atomizing a small amount of liquid and applying it to an object to be coated,
A liquid supply passage;
The tip is needle-shaped and the needle is very thin with a uniform gradient to the tip .
A valve mechanism is formed between the tip of the needle and has a very fine first nozzle hole having a shape corresponding to the needle tip, and the needle tip can be inserted into and removed from the first nozzle hole. A first nozzle that can be fitted to
A second nozzle that surrounds the first nozzle and forms an annular first atomizing compressed gas passage between the first nozzle and a second nozzle hole having a small diameter at the lower end;
The third nozzle of the third nozzle is formed at the lower end of the second nozzle so as to surround the second nozzle hole of the second nozzle and the lower end protrudes from the lower surface of the second nozzle by a predetermined distance. hole is formed, around the third nozzle holes, to flow compressed gas for the second atomization and swirling flow formed along the opposite conical inclined surface is an outer wall, said second atomization A third nozzle formed with a plurality of compressed gas supply passages for forming a swirl flow for use;
A needle movement amount adjusting device which is provided so as to be in contact with a rear end portion of the needle, and which can adjust a very small amount of an opening gap between the tip portion of the needle needle and the first nozzle hole of the first nozzle;
With
The tip of the needle protrudes to the inside of the third nozzle hole of the third nozzle with the valve mechanism opened, and the liquid goes to the tip between the first nozzle hole and the needle tip. A structure that oozes along the tip of the ultrafine needle while passing through a very small gap as the annular gap becomes smaller,
While the liquid is discharged, the second nozzle is atomized by the first atomizing compressed gas flowing through the first atomizing compressed gas passage while the liquid oozes from the first nozzle hole of the first nozzle along the tip of the needle. Jetting from the second nozzle hole of the nozzle, and then causing the jet stream to jet through the third nozzle hole of the third nozzle and causing the compressed gas for forming the second atomization and swirl flow to collide with the jet stream, A spraying device for a small amount of liquid, characterized in that the jet stream is further atomized, swirled and diffused, and applied to an object to be coated. The liquid supplied to the liquid supply passage has a low viscosity of 10 to 100 CPS, the outlet diameter of the first nozzle hole of the first nozzle is 0.2 to 0.6 mm, and the needle needle The angle of the tip is 3 to 10 degrees, the opening inner diameter of the second nozzle hole of the second nozzle is 0.8 to 1.5 mm, and the opening diameter of the third nozzle hole of the third nozzle is 1. The moving distance of the needle for adjusting an extremely small opening gap between the tip of the needle needle and the first nozzle hole of the first nozzle by the needle moving amount adjusting device is 0 to 2.0 mm. The spraying of a small amount of liquid according to claim 1, wherein a small amount of liquid is atomized and applied by adjusting the liquid discharge amount to 0.1 to 10.0 cm ³ / min. apparatus.

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